LED Pattern Flatness Measurement for Reflective Steel Sheet
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Solution Overview
Problem
Conventional methods for measuring the flatness of hot-rolled steel sheets, particularly in high-speed manufacturing processes, face challenges such as reduced measurement accuracy due to high specular reflectivity and the need for large, cumbersome measurement apparatuses, which complicates installation and increases heat generation.
Innovation Solution
The use of an LED light source with a staggered pattern of LEDs, where the longitudinal and lateral directions are aligned with the sheet's lengthwise and widthwise directions, respectively, allows for accurate flatness measurement without requiring a large-scale apparatus. This setup includes a two-dimensional camera with an electronic shutter for synchronous lighting and exposure, minimizing heat generation and improving measurement resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional large-scale measurement apparatus is used to measure flatness of hot-rolled steel sheets, then measurement accuracy can be maintained, but the apparatus requires large installation space and generates excessive heat
Solution Approach 1:
The patent segments the measurement system into multiple independent LED light sources arranged in a specific pattern, replacing the conventional single large-scale apparatus. This segmentation allows the system to maintain measurement accuracy while reducing the overall installation space requirements and heat generation from any single component.
Solution Approach 2:
The patent changes the illumination parameters by using multiple LED light sources with specific luminous intensities and arrangement patterns, replacing conventional large-scale illumination systems. This parameter change enables accurate flatness measurement with reduced installation space and lower heat generation.
2Area of stationary object
If the image pickup device receives specularly reflected light from the steel sheet surface, then measurement can be performed in compact setup, but measurement accuracy deteriorates due to high reflectivity
Solution Approach 1:
The patent applies local quality by assigning different luminous intensities to different LED light sources based on their positions and the local reflection characteristics of the steel sheet surface. This allows the system to compensate for specular reflection effects locally while maintaining accurate flatness measurement in a compact setup.
Solution Approach 2:
The patent uses an asymmetric arrangement of LED light sources with different luminous intensities rather than a symmetric uniform illumination pattern. This asymmetric configuration optimizes the illumination to account for specular reflection characteristics, enabling accurate measurement in compact installations.
3Illumination intensity
If conventional light sources are used to illuminate the steel sheet surface, then sufficient illumination is provided, but the apparatus becomes large-scale and generates excessive heat
Solution Approach 1:
The patent segments the illumination system into multiple LED light sources that can be distributed across the measurement area. This segmentation provides sufficient total illumination intensity while each individual LED generates minimal heat, avoiding the excessive heat generation problem of conventional large-scale light sources.
Solution Approach 2:
The patent replaces conventional thermal-based large-scale light sources with LED technology, which uses electroluminescence instead of thermal radiation. This substitution maintains sufficient illumination intensity while dramatically reducing heat generation and apparatus size.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise measurement of flatness with reduced installation space requirements and improved measurement resolution, even when the image pickup device receives specularly reflected light, maintaining high accuracy and productivity in steel sheet manufacturing.
Implementation Method 1
an LED light source including a plurality of LEDs disposed at a predetermined pitch respectively in longitudinal and lateral directions
Implementation Method 2
even when the image pickup device receives specularly reflected light
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A method for measuring a flatness of a sheet material according to the present invention comprises: projecting a bright and dark pattern P made up of bright parts and dark parts onto a surface of a sheet material S travelling in a lengthwise direction; picking up an image of the bright and dark pattern with image pickup device 2 to acquire a pattern image, the image pickup device having a field of view larger than a width of the sheet material; and analyzing the acquired pattern image to measure the flatness of the sheet material, wherein a bright and dark pattern in which a bright part is disposed at a predetermined set pitch respectively in longitudinal and lateral directions is formed by light emitted from an LED light source including a plurality of LEDs disposed at a predetermined pitch respectively in the longitudinal and lateral directions, and the bright and dark pattern is projected onto the surface of the sheet material such that the longitudinal direction of the bright and dark pattern lies along a lengthwise direction of the sheet material, and the lateral direction of the bright and dark pattern lies along a width direction of the sheet material.